1. Field of the Invention
The present invention relates generally to clock recovery.
2. Background Art
Conventional voltage controlled oscillator (VCO) calibration and/or clock and data recovery (CDR) require a reference clock in order to bring the VCO output frequency in the vicinity of the data rate before phase acquisition.
In certain applications, such as power and/or area-limited circuits, a reference clock may not be present or may be difficult to route. Accordingly, there is a need for reference-less VCO calibration and/or CDR techniques. In addition, it is desirable that VCO calibration and/or CDR techniques be minimally susceptible to the presence of jitter and inter-symbol interference (ISI) on the data and clock jitter in the VCO output.
The present invention will be described with reference to the accompanying drawings. Generally, the drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.